1. Please put your name at the top of the whiteboard and sketch these axesv t

2. A student enters college at the main entrance, walks to the physics room, then returns a book to the library, then goes to see a friend at the refectory. She then leaves college by the main entrance. Just considering the vertical movement…
on the top set of axes, sketch the corresponding displacement-time graph
on the bottom set of axes, sketch a velocity-time graph for her time in college, taking upwards as the positive direction. (Remember the gradient of the s/t graph is the value of the v/t graph)

3. Sketch these axes on your whiteboardv t

4. Summary from last week s
The gradient of the s/t graph gives you the velocity
The area under the v/t graph gives you the displacement v t
The gradient of the v/t graph gives you the acceleration
The area under the a/t graph gives you the velocity a t

5. I will collect in those that have only just completed them
Have a look at your homework sheets, we’re going to check the mark scheme
I will collect in those that have only just completed them

9. aims Build on our knowledge of graphs of motion
Know the meaning of the symbols
Use equations for uniform acceleration
Link these two areas of knowledge

10. Motion along a straight line with constant (uniform) acceleration
Initial velocity, u
Final velocity, v
Acceleration, a = constant
displacement, s
time, t

11. Motion along a straight line with constant (uniform) acceleration
Velocity v
v-u u
On your whiteboard, rearrange this equation to make v the subject:
v = t
Equation 1
Time

12. Motion along a straight line with constant (uniform) acceleration
Velocity
Area under graph = displacement
Displacement = area of trapezium
= average height x base
= average velocity x time
= (u + v) t v 2 u
Equation 2 t
Time

13. Motion along a straight line with constant (uniform) acceleration
Area under graph = displacement
Velocity v
v-u u
Equation 3 t

14. Motion along a straight line with constant (uniform) acceleration
For those who like a mathematical challenge:
Rearrange equation 1 to make t the subject
Use this to eliminate t from equation 2
Simplify and rearrange to make v2 the subject
Equation 4

15. Summary – write this bit down
The equations of motion for:
Motion along a straight line with constant (uniform) acceleration
s = displacement (m)
u = initial velocity (ms-1)
v = final velocity (ms-1)
a = acceleration (ms-2)
t = time (s)

16. Which equation? Use this method: Write down the 5 symbols
1) An object travelling at 15ms-1 accelerates at 3 ms-2 for 5 seconds.
Calculate
its final velocity
its displacement
Which equation?
Use this method:
Write down the 5 symbols
Fill in the 3 values given
Put ‘?’ by the one you are asked for
Select the equation that doesn’t have the blank symbol
You may need to rearrange the equation s = u v a t
15 ms-1
3 ms-2
5 s ?

17. 1) An object travelling at 15ms-1 accelerates at 3 ms-2 for 5 seconds.
Calculate
its final velocity
its displacement a) s = m u
ms-1 v a
ms-2 t
112.5 15 30 ? b) 3 5

18. (a) distance travelled in first 7 seconds
Equations of Motion Questions
Remember that you can only apply suvat when the acceleration is constant.
You may need to split problems in to parts.
2) A car travels in a straight line at 25ms-1 for 7 seconds then slows to a stop at a constant rate in 5 seconds. Calculate
(a) distance travelled in first 7 seconds
(b) its acceleration during the last 5 seconds
(c) the total distance travelled.
3) An arrow accelerates from rest at 300ms-2 through a distance of 0.5m. It then flies at steady speed 20m to a target. Calculate the total time from rest until hitting the target.

19. (a) distance travelled in first 7 seconds
2) A car travels at 25ms-1 for 7 seconds then slows to a halt in 5 seconds. Calculate
(a) distance travelled in first 7 seconds
(b) its acceleration during the last 5 seconds
(c) the total distance travelled.
Part b s = m u =
ms-1 v = a
= ?
ms-2 t =
Motion is in two parts:
velocity/ms-1
time/s 25 7 12 a) b)

20. (a) distance travelled in first 7 seconds
2) A car travels at 25ms-1 for 7 seconds then slows to a halt in 5 seconds. Calculate
(a) distance travelled in first 7 seconds
(b) its acceleration during the last 5 seconds
(c) the total distance travelled.
a) s = 175m
Part c
Add distances from a) and c) : total distance = 237.5m

21. 3) An arrow accelerates from rest at 300ms-2 through a distance of 0
3) An arrow accelerates from rest at 300ms-2 through a distance of 0.5m. It then flies at steady speed 20m to a target. Calculate the total time from rest until hitting the target.
Motion is in two parts, the first part the arrow is accelerating and the second part the arrow is at a constant speed.
Find the time for the first part s = m u =
ms-1 v = a =
ms-2 t
= ?

22. 3) An arrow accelerates from rest at 300ms-2 through a distance of 0
3) An arrow accelerates from rest at 300ms-2 through a distance of 0.5m. It then flies at steady speed 20m to a target. Calculate the total time from rest until hitting the target.
Motion is in two parts, the first part the arrow is accelerating and the second part the arrow is at a constant speed.
Find the final velocity to find the value for constant speed for the second part s = m u =
ms-1 v
= ? a =
ms-2 t =
Final velocity at end of acceleration = constant velocity in the second stage.
In second (constant velocity) stage:
v = s / t so t = s / v = 20/17.3 =1.156s
Add the times from the 1st and 2nd part: = 1.21s (3sf)

23. Lets see how we’re all doing by trying an exam question
You have 7 minutes
Please work on your own for this
BUT
Don’t panic, its not a test!

25. aims Build on our knowledge of graphs of motion
Know the meaning of the symbols
Use equations for uniform acceleration
Link these two areas of knowledge

26. June 2002

27. This is called “freefall”, more on this next week!
Last question
An object falls from rest through a distance of 3m
with a constant acceleration of 9.81ms-2 downwards.
Calculate
its final velocity
(b) the time taken
We don’t really need this bit as all objects released near the earth will accelerate towards it at 9.81ms-2.
This is called “freefall”, more on this next week!
7.7ms-1
0.78s

29. Homework Will be e-mailed out once a week
Will be split into two sets of tasks, one for each teacher
Will make clear when the tasks will be checked next week
Support available Thursday and Friday at lunchtimes
Next time – freefall and projectiles